All divers, novice through experienced, face challenges when navigating underwater. Open water diver certification programs include instruction on basic navigation skills for use in dive activities. These programs are generally limited to instruction on how to read a compass underwater and how to swim in a fixed direction for a fixed time and how to return to a start location after reversing the swim direction using readings from the compass. However, these underwater navigation skills are difficult for many divers to master and therefore, a typical diver may never use the skills in diving expeditions.
Even if performed properly, the compass-based underwater navigation technique leaves much to be desired. First, the technique does not take into account underwater currents which can be both strong and invisible and can make it very difficult for a diver to estimate error which is introduced into the diver's navigation path as a result of the currents, much less compensate for the error. Second, it does not account for non-straight line paths which may be either necessary to circumnavigate obstacles or desirable to enjoy viewing features that are off the chosen path in caves and channels, etc.
In addition, it should be noted that even in high visibility areas, a dive boat from which a diver descended into the water may be 60 to 100 feet above the diver and may provide almost no cues to the diver that he or she is directly under the boat unless the diver approaches the surface or encounters and follows a mooring line. A 100-foot dive boat may not even cast a visible shadow when viewed directly from the bottom. This situation is only aggravated by many typical dive sites with less than optimal visibility.
Abandoning use of a compass for underwater navigation can be very disorienting to a diver since many dive sites have silting and low visibility and are mixtures of coral heads, sand beds, and other features which are very similar to each other over a wide area, making landmark recognition and tracking problematic. As a result, it is quite common for even experienced divers to rely on guides who are familiar with a dive site with which the diver is unfamiliar so that the diver can relax and view the surroundings knowing that his or her guide is responsible for safely returning the diver to the boat.
Another indication of the need for an effective device to aid in underwater navigation is the existence of several alternate solutions which have attempted to meet this need. There are several underwater navigation methods that are utilized by commercially-available products. All of these products attempt to address the issues described above but fall short of fully enabling a diver to explore an underwater setting as if the diver were being guided by a human guide. The products typically have limited range from the diver's starting point or from the point on the surface of the water at which the diver begins the dive. In addition, their accuracy and basic functions are commonly compromised for a variety of reasons.
Conventional underwater navigation systems include sonic range finders and GPS-based systems. These systems suffer, however, from several disadvantages in an underwater environment. First, in operation of these systems the diver must remain tethered to the dive boat or other surface component via some sort of signal line or antenna cable. This severely limits travel depth and mobility during a dive. Typical systems implemented with this method use cable lengths of fifty feet or less so that divers using these devices are limited to only relatively shallow dives. In addition, because the diver is tied to a surface line, the freedom that is provided by SCUBA (Self Contained Underwater Breathing Apparatus) is compromised. Mobility to travel through wrecks, coral heads and any features which do not provide a direct line path to the surface becomes problematic. A device which should provide enhanced safety and enjoyment may itself become a safety hazard by increasing the probability that a diver may become entangled by the surface line.
A need therefore remains for an improved personal underwater navigation system provides a diver a straight return path back to a starting point.